ImplicitBoolean

Introduction

vtkImplicitBoolean enables boolean combinations of implicit functions like Plane, Sphere, Cylinder, and Box. Operations include union, intersection, and difference. Multiple implicit functions can be specified (all combined with the same operation).

operation (set/get)

Specify the operation to use: ‘UNION’ (<=0), ‘INTERSECTION’ (=1), ‘DIFFERENCE’ (>=2)

addFunction(actor) / removeFunction(actor) / getFunctions() : []

Add an implicit function to the list of functions.

evaluateFunction(xyz)

Given the point xyz (three floating values) evaluate the boolean combination of
implicit functions to return the combined function value.

evaluateGradient(xyz)

Given the point xyz (three floating values) evaluate the boolean combination of
implicit functions to return the combined gradient value. The method returns an array of three floats.

Source

Constants.js

// Constants in support of ImplicitBoolean
//
export const Operation = {
  UNION: 0,
  INTERSECTION: 1,
  DIFFERENCE: 2,
};

export default {
  Operation,
};

index.js

import macro from 'vtk.js/Sources/macros';
import Constants from 'vtk.js/Sources/Common/DataModel/ImplicitBoolean/Constants';
import vtkImplicitFunction from 'vtk.js/Sources/Common/DataModel/ImplicitFunction';

const { Operation } = Constants;

// ----------------------------------------------------------------------------
// Global methods
// ----------------------------------------------------------------------------

// ----------------------------------------------------------------------------
// Static API
// ----------------------------------------------------------------------------

// ----------------------------------------------------------------------------
// vtkImplicitBoolean methods
// ----------------------------------------------------------------------------

function vtkImplicitBoolean(publicAPI, model) {
  // Set our className
  model.classHierarchy.push('vtkImplicitBoolean');

  // Capture "parentClass" api for internal use
  const superClass = { ...publicAPI };

  publicAPI.getMTime = () => {
    let mTime = superClass.getMTime();
    if (!model.functions || model.functions.length <= 0) {
      return mTime;
    }

    for (let i = 0; i < model.functions.length; ++i) {
      mTime = Math.max(mTime, model.functions[i].getMTime());
    }
    return mTime;
  };

  publicAPI.getOperationAsString = () =>
    macro.enumToString(Operation, model.operation);

  publicAPI.setOperationToUnion = () => publicAPI.setOperation(0);
  publicAPI.setOperationToIntersection = () => publicAPI.setOperation(1);
  publicAPI.setOperationToDifference = () => publicAPI.setOperation(2);

  publicAPI.getFunctions = () => model.functions;
  publicAPI.hasFunction = (f) =>
    !!model.functions.filter((item) => item === f).length;
  publicAPI.addFunction = (f) => {
    if (f && !publicAPI.hasFunction(f)) {
      model.functions = model.functions.concat(f);
    }
  };

  publicAPI.removeFunction = (f) => {
    const newFunctionList = model.functions.filter((item) => item !== f);
    if (model.functions.length !== newFunctionList.length) {
      model.functions = newFunctionList;
    }
  };

  publicAPI.removeAllFunctions = () => {
    model.functions = [];
  };

  publicAPI.evaluateFunction = (xyz) => {
    let value = 0.0;
    if (model.functions.length <= 0) {
      return value;
    }

    if (model.operation === Operation.UNION) {
      value = Number.MAX_VALUE;
      for (let i = 0; i < model.functions.length; ++i) {
        const f = model.functions[i];
        const v = f.functionValue(xyz);
        if (v < value) {
          value = v;
        }
      }
    } else if (model.operation === Operation.INTERSECTION) {
      value = -Number.MAX_VALUE;
      for (let i = 0; i < model.functions.length; ++i) {
        const f = model.functions[i];
        const v = f.functionValue(xyz);
        if (v > value) {
          value = v;
        }
      }
    } else {
      const firstF = model.functions[0];
      value = firstF.functionValue(xyz);
      for (let i = 1; i < model.functions.length; ++i) {
        const f = model.functions[i];
        const v = -1.0 * f.evaluateFunction(xyz);
        if (v > value) {
          value = v;
        }
      }
    }
    return value;
  };

  publicAPI.evaluateGradient = (xyz) => {
    const t =
      model.axis[0] * (xyz[0] - model.center[0]) +
      model.axis[1] * (xyz[1] - model.center[1]) +
      model.axis[2] * (xyz[2] - model.center[2]);

    const cp = new Float32Array(3);
    cp[0] = model.center[0] + t * model.axis[0];
    cp[1] = model.center[1] + t * model.axis[1];
    cp[2] = model.center[2] + t * model.axis[2];

    const retVal = [
      2.0 * (xyz[0] - cp[0]),
      2.0 * (xyz[1] - cp[1]),
      2.0 * (xyz[2] - cp[2]),
    ];
    return retVal;
  };
}

// ----------------------------------------------------------------------------
// Object factory
// ----------------------------------------------------------------------------
const DEFAULT_VALUES = {
  operation: 0,
  functions: [],
};

// ----------------------------------------------------------------------------

export function extend(publicAPI, model, initialValues = {}) {
  Object.assign(model, DEFAULT_VALUES, initialValues);

  // Object methods
  vtkImplicitFunction.extend(publicAPI, model, initialValues);

  macro.setGet(publicAPI, model, ['operation']);

  vtkImplicitBoolean(publicAPI, model);
}

// ----------------------------------------------------------------------------

export const newInstance = macro.newInstance(extend, 'vtkImplicitBoolean');

// ----------------------------------------------------------------------------

export default { newInstance, extend, ...Constants };